One of the weaknesses of conventional breath alcohol testing equipment is its inability to discriminate volatile constituents of the breath different from ethanol which produce an output from an infra-red cell. Various methods and apparatus have been proposed to discriminate these contaminants, and some of them are quite effective in detecting such things as toluene, but none has been effective in detecting alcohols closely related to ethanol, such as methanol, propanol and isopropanol. The burden of proof in cases involving driving while intoxicated, when the evidence is the result of a breath test, has become heavy in many jurisdictions, and it is important to be able to convince a court that the result was not anomalous by virtue of the presence of methanol, for example.
In the method of the present invention, amounts of methanol constituting as little a five percent of the total alcohol content of breath samples can be detected.
One of the objects of this invention is to provide a method of discriminating contaminants in the nature of alcohols different from but closely related to ethanol in a breath alcohol testing device.
Another object is to provide apparatus for accomplishing the method.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.